1. Field of the Invention
The present invention relates to ionic and/or nonionic aqueous polyurethane dispersions based on 1-methyl-2,4- and/or -2,6-diisocyanatocyclohexane, aqueous binder compositions containing these aqueous polyurethane dispersions and known crosslinking resins and the use of the dispersions and binder compositions as binders for glass fiber sizings.
2. Description of the Prior Art
Polyurethane dispersions are known and described, e.g., in DE-A 1,495,745, 2,645,779, 3,903,538, 4,137,661 and 4,219,418, and in Kunststoffhandbuch Vol. 7, 3rd edition, 1993, pp. 30 and 31. They are also described in D. Dieterich, Angew. Makromol. Chem. 98 (1981) 133 and H. Reiff, D. Dieterich, Angew. Makromol. Chem. 26 (1972) 85. The aqueous polyurethane dispersions described in these prior publications can be used to prepare paints or coatings with excellent properties, which can be used for various applications according to their composition.
It has now been found that aqueous polyurethane dispersions which contain as a main structural component 1-methyl-2,4- and/or -2,6-diisocyanatocyclohexane incorporated through urethane groups and optionally through urea groups possess, in addition to excellent properties, very good viscosity stability during storage when compared to known systems.
It has further been found that when these aqueous polyurethane dispersions are used as binders for glass fiber sizings, the glass-fiber-reinforced plastics have outstanding mechanical properties. Significantly improved processability during manufacture and use of the sized glass fibers was also observed. A further advantage of the sized glass fibers according to the invention is their low bulk volume.